1. Field of the Invention
This invention relates to devices for controlling power input to motors, and particularly to a motor system wherein the input potential to an A.C. induction motor is controlled proportional to a load on the motor.
2. General Description of the Prior Art
U.S. Pat. No. 4,052,648 describes a system wherein the phase difference between the voltage applied to a motor and current through the motor is detected, and the duty cycle of a triac connected in series with the motor is decreased with an increase in phase angle. By this technique, an unloaded motor is caused to draw less power. In this manner, significant power savings can be achieved inasmuch as many motors operate at times with less than a full load. The system of referenced patent requires a number of components, and it is the object of this invention to provide a motor system wherein both the power input to a motor is decreased with a decreased load, and this is accomplished with fewer components and at less cost.